I'd not eff w/ yer headrests too much, if the worm drive / gear are anything like those in my e28... destined to walk the shaft out of the gear 8-). Which always occurs only at the headrest's exact apogee of furthestest possable extension, of course. (fear not, my //S8's headrests were the same story... sad).

I've learned not to touch certain things (no, not that, touchaway there). I keep awaiting the day my "convenience entry" steering wheel (pronounced fukkinannoying) in this M5's eff's the pooch... of course in the Buick Roadmaster northmost position. Can only turn it off w/ speshul tewl of course. I'm a special tool, but not that special.

boy, you'll have the Trifecta of Incessant Neediness there with that fleet of yours lol... promises to keep you - um - busy